templatekw: make negrev return empty for wdir() and nullrev I considered just returning the same output that {rev} returns here, but {rev} also returns essentially gibberish: either an INT_MAX-kind of variable for wdir() or -1 for null. Since these are numbers that are intended to be used for calculations, and since the numbers for wdir() and -1 are not really very helpful for calculation (and worse, when used as a revision number -1 is equal to unhidden tip), I figured the most reasonable thing to do here is to just return nothing for negrev. This could potentially break scripts that are expecting to parse a nonempty integer out of a {negrev}, but that seems like a very remote concern at this juncture.